For a Stock Rifle, Bushmaster makes a Very Nice Varmint Rifle. It's in the price range you want. The barrel is 24" for the added velocity. It has a "Comp" trigger and a Free Float Tube already. It doesn't have the front sight as it's ment for optics but you could easily add a front site post. Out of the Box it's a great rifle. The Colt you mentioned sounds good also. What model is it? If it's a Sporter it would be a good buy. Also consider the Bushmaster DCM. You can see it at their web site as well as the varminter. I know they will drive tacks as well but they are a little more money. DCMP makes the Panther Clasic which also falls right in with these other rifles. They also have several Stainless Bull Barrel models which are very accurate. Olympic makes the Ultramatch rifle, but like the varmint rifle Bushy has, it doesn't have a front sight since it's made for optics. Olympic also makes the PCM-1P which I've read very good things about as far as accuricy. I own a Bushy, Olympic, Colt and DPMS and all are fantastic rifles. Colt is more $ but they also are a little nicer as far as finish. Finished barrel under the front site post and things like that shows they are paying attention to detail and also explains why they cost a little more. I don't think you can buy a Armalite, Bushy, Colt, DCMP or Olympic and not be satisfied. Unless you are strictly looking for a "National Match" rifle, they will all have small differences and different "stock" options that will help you determine your final choice.
Good luck and keep us posted as to what you end up buying.
Semper Fi